Hash class to implement Compareable

[Hummus-Ful]

Hey,

I use a HashMap object to store key, value pairs where the Hash object of each photo is used as a key.
I tried switching to TreeMap object as it provides automatic sorting of the entries it stores, but because the Hash class does not implements Compareable, I cant use Hash as key anymore and I have to workaround using BigInteger (using the getHashValue) or converting the Hash to string object.

If possible, I would like Hash class to implement Compareable so it can be used directly in a TreeMap.